TITUSVILLE — Merritt Island residents are expected to gather in force Tuesday to ask Brevard County commissioners to return 140 acres of wetlands near the barge canal from a heavy industrial use to its original zoning.

Their request is part of a lengthy zoning battle involving environmental issues, property ownership rights and public policy on where Brevard's future industrial development should be.

For four years homeowners have tried to reverse the former commission's April 1982 decision that changed the property's zoning from a non-specific use to heavy industry.

The change was to allow United Space Boosters Inc. to build a booster rocket manufacturing plant on the site, just north of the barge canal. However, residents so vehemently protested the plant and a proposal to store hazardous waste there that it was moved to Kennedy Space Center.

The land, owned by Cocoa Beach investor John Kabboord, was sold in October 1984 to North Merritt Marina Inc. for $1.5 million. Today it lies fallow. But residents worry that the heavy industry zoning will open the door to manufacturing that could harm the wetlands and homeowners.

''On the north side of that barge canal is some of the most environmentally sensitive land in the county,'' said resident Carol Hayes. ''Heavy industry there sets a precedent for more heavy industry.''

But Merritt Island attorney Leonard Spielvogel, who represents North Merritt Marina Inc., said the residents are creating a ''scare situation'' that could cause more harm than good.

''You're encouraging people to develop the property so they can get vested rights,'' he said. Spielvogel declined to say what his client plans for the property, although he said environmental factors are being considered.

The homeowners say there are several things in their favor: an environment- conscious county commission, and a 1982 zoning review that questions the land's suitability for industrial use and shows it never was reviewed for heavy industry.

Weighing against the homeowners are county officials who say the industrial zoning doesn't conflict with Brevard's land-use plan. And officials are concerned that returning the property to its former zoning could spark a costly lawsuit by the landowner that the county may not win.

''I certainly have environmental concerns,'' Commissioner Charlie Roberts said. ''But if you go in with an administrative rezoning, you're certainly facing a lawsuit -- and one you might lose.''

County ordinances allow the commission to rezone property without the consent of the landowner if the change is deemed in the public interest. But there are other legal considerations, such as a property owner's vested interest and grandfather clauses.

Spielvogel said the owner opposes the rezoning request, but he declined to say if it would sue.

Brevard zoning officials have recommended the commission delay action until the county's new comprehensive land-use plan is finished this summer. The plan is expected to recommend against heavy industrial use in the barge canal area, officials said.

''My stance was then -- and is now -- that the barge canal has been zoned light industry and should remain so. Heavy industry should be at the Cape Canaveral port,'' Roberts said.

''If you have a comprehensive plan in hand and then administratively rezone, you're in a much better position to fend off any lawsuit that might be the outcome,'' he added.

But the homeowners disagree, saying the property could be developed by the time the plan makes it through the lengthy review and approval process in Tallahassee.

''Even if that plan recommends against heavy industry use, that simply strengthens'' the argument that the owner ought to be allowed to keep the zoning that came with purchase of the property, Merritt Island resident Bill Patterson said.

Meanwhile, residents are gearing up for a showdown. They have argued repeatedly that the property never should have been rezoned because Kabboord's February 1982 rezoning application asked for a change to light, not heavy, industry.

But county attorney Frank Griffith, whose firm represented Kabboord and United Space Boosters in the land sale, changed a newspaper legal ad for the March 1982 public hearing to designate the rezoning request as heavy industry. It was done without the staff's knowledge, county records show.

The residents complained to The Florida Bar, which found no improprieties. Residents say the ad was changed to comply with the 1981 contract between Kabboord and United Space Boosters, which agreed to buy the property contingent on a zoning change to heavy industry.

''We feel it was rezoned illegally from the beginning,'' Hayes said. ''But the county attorney told the commission his decision was legal, and if the board reversed the zoning it would face a lawsuit.''

However, Hayes said, ''It is an election year, and I believe in miracles.''